RFR: 8273435: Remove redundant zero-length check in ClassDesc.of

[Andrey Turbanov]

On Wed, 18 Aug 2021 07:28:57 GMT, Andrey Turbanov <github.com+741251+turbanoff at openjdk.org> wrote:

> After [JDK-8215510](https://bugs.openjdk.java.net/browse/JDK-8215510) (eed3a536c0) this condition is always `false`. Empty package name is handled separately.
> Found by IntelliJ inspection.

Can someone sponsor changes, please?

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PR: https://git.openjdk.java.net/jdk/pull/5157